|About multi-store and domains|
|If you see the following message, there are 3 possible main causes:
Scenario 1: Scope configuration
Firstly, it isn't necessarily an error message, if you see this message in either a store view or website scope, and this scope is inheriting the configuration from its parent, the message is ok, it just means that the specific scope you are seeing has its data being sent by a parent scope (either a website or the default configuration), so if this is the case please ignore the message, there is nothing wrong.
As an additional note have also in mind that even if a store is created in the default scope, if all store views and/or websites are using their own configuration, the default scope will not send anything because no one is inheriting from it.
But, if you see this message in the default scope, or on a store view or website which you have set up independently, there are 2 remaining possible causes:
There has been a new change in the MailChimp API, they don’t allow multiple stores with the same domain to be created.
It seems you either have another Magento store setup with the same domain or there is an orphan store created in MailChimp with that domain.
Scenario 2: Using multi-store with the same domain under a Mailchimp account.
When you are using multi-store enabling the extension in more than one store view and/or website, then you will need a different domain for each of them or otherwise only the first one will be created, but the rest will give you the error. So you'll need to make sure each store view or website has its own domain, one way to do this easily is adding a store code to the base URL, check the Magento documentation to find out how to do this, or the links below:
Magento 1: https://php.quicoto.com/how-to-add-store-codes-in-url-magento/
Magento 2: https://devdocs.magento.com/guides/v2.1/config-guide/multi-site/ms_websites.html (Check step 6)
You should be at least on version 1.1.12 for this to work properly (Magento 1) or 1.0.30 with mailchimp-lib 3.0.28 (Magento 2)
Scenario 3: Orphan Mailchimp Store
This will not work in all occasions, but only in the cases that your orphan store appears in 'Connected Sites' in MailChimp. If this is the case, clicking on the 'Disconnect' button should also delete the store from Mailchimp, not making it necessary to do it via Postman.